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Joins to utilizes outer tables min/max values of join columns
If one has select statement of type
inner join T2 on T1.A = T2.A
T1.B = 'something'
The table T1 typically full scanned (T1.B does not have index) and table T2 is full scanned or accessed by index.
If table T2 is big, then join operation using full scan can take a quite a lot of time; temporary areas used for joining can be large.
If during scanning of table T1 the max and min values of T1.A where stored, and when accessing table T2 this information would be utilized,
there might be possibility to utilize partition pruning or discarding of not applicable rows for temporary areas.
The max and min values of T1.A could be gotten easily during scanning of rows, no extra sorting would be required.
Then joining of these tables might utilize less resources.